Impacts from open loop scrubbers

scrubber concerns There are concerns over open loop scrubbers in ports

COMMENT: Having heard rumours about open loop scrubbers adversely affecting sediment in British harbours this year, it came as little surprise when the media announced a story in late October, writes Charles Haine.

The reveal is that these scrubbers pollute the sea – and seabed – instead of the air, despite reaching compliance with the IMO’s requirement to use fuel oil with 0.5% sulphur content (existing is 3.5%).

The headline, from The Independent, was even more spectacular: “Environmental ‘cheat devices’ fitted to thousands of ships could render UK ports unusable”. Scrubbers work by spraying exhaust gases with seawater to capture sulphur dioxide.

‘Open loop’ scrubbers allow the discharge of the resulting acidic and contaminated (e.g. by sulphite, heavy metals such as lead and zinc, soot particles) wash waters into the sea. In turn, these pollutant wastes settle onto and into sediment and significantly increase the cost of dredging.

The global shipping industry has spent a substantial $12bn (£9.7bn) on scrubbers in around 3,700 vessels, with 500 now in service. Despite being heavy units and not helping fuel efficiency, the return on investment is said to be one year.

The approach is allowed under IMO guidelines and is cheaper than purchasing cleaner fuel, at $300-500 more, per tonne. Less than 2% (65) of scrubbers are ‘closed loop’ systems that store the extracted wash waters in tanks before discharging to an appropriate waste reception facility on the landside when in port.

Problems are guaranteed to occur where dumped scrubber wastewater build-up pollutants after repeat visits in navigation channels, turning circles and berths. Ports are rightly worried that the accumulations of polluted sediment will warrant the deployment of considerable mitigation measures to avoid and prevent the resuspension of contaminants. Those can ingress into ecosystems, and ultimately the food chain.

A 2015 study by Umweltbundesamt – UBA (the German environment agency), concluded the use of open loop scrubbers causes environmental degradation through short-term and spatially limited Ph value reduction, an increase in temperature and turbidity alongside discharge of sometimes persistent materials.

With the annual cost of maintenance and capital works dredging already costing many millions, the increased outlay including programmes to manage hotspots of contamination might require an investment that could put a port out of business. Isolating and capturing contaminants underwater is a time-consuming and difficult activity. Likewise, the disposal – usually at dump sites offshore – will require studies, modelling, licences and new contracts with marine contractors.

Any instruction to treat or remediate contaminated seabed could prove to be tens of times costlier than disposing of non-contaminated dredged material. The conundrum comes from ports and terminals being reliant on visiting vessels but now suffering an increase in risk from a new, and potentially long-term pollution source. Port authority engagement with vessels, and terminals, and the policing of ships’ activities are yet another area for attention.

Vessels should not be discharging such wastes into the marine environment, let alone in ports. Ports have got to grips with much better water and sediment quality in their harbours in the last few decades and there is short-term evidence this is now being compromised by vessels with open loop scrubbers. The backlash is underway. China, Fujairah (UAE) and Singapore will ban the use of open loop scrubbers, from the start of 2020, to coincide with the IMO MARPOL Regulations on the topic coming into force.

Individual ports in Ireland, Finland, Lithuania, the Russian Federation and the UK are all banning or restricting the discharge of scrubber wastes in their waters. Norway may be considering an outright ban on all types of scrubbers. Environmental and sustainability initiatives in the maritime sector from the Poseidon Principles through to loans for CAPEX expansion projects will undoubtedly prohibit the use of open loop scrubbers in the future.

The law of unintended consequences illuminates the perverse unanticipated effects of legislation and regulations. The push to meet the IMO’s 2020 deadline on 0.5% sulphur in marine fuel oil will certainly help air quality, but at a potentially serious cost to the marine environment.

The implications for smaller ports that host cruise and/or cargo vessels are potentially disastrous. Anticipate more scrutiny and the need for marine surveys in the aquatic environment to measure and confirm these startling risks and hazards.


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